This paper presents the effect of barium silicate nanoparticle on the performance and the hydration characteristics of alkali- activated slag. Low sodium oxide (2.33 wt%) was chosen to mitigate the environmental impact of alkali and its corrosive effect on the user. Owing to the use of low sodium oxide content, the control sample recorded a modest 28-day compressive strength (27 MPa). Adding nano barium silicate enhanced the compressive strength significantly. The hardened sample having 0.5 and 1.0 wt% achieved 28-day compressive strength values of ∼38 and 50 MPa, respectively. Increasing nBS content up to 1.5 wt% led to a regression in me- chanical properties, but is still higher than the reference sample. Nevertheless, all nano-modified-mixtures showed shorter setting times and higher workability than the mixture with no nanomaterial. Additionally, the hydration products compositions strongly in- fluenced by nano barium silicate addition, where a significant change in calcium to silica ratio and silica to alumina ratio inside cal- cium aluminosilicate hydrate binding phase was detected with nanomaterial addition (especially at addition level of 1.0 wt%). The use of thermally treated nanobarium silicate at 800 °C instead of untreated one resulted in a notable decrease in the performance of alkali-activated slag, suggesting the negative role of thermal treatment on the reactivity of nanomaterial. The investigated mixture containing 1.0 wt% nanobarium silicate achieved the sustainability concept, as it recorded best rheology, highest compressive strength, and low sodium and barium leachability, despite of using low sodium oxide content.